codenothing/CSSCompressor

/**
 * 
 * Shrink Hex
 * 
 * @author: Corey Hart <http://www.codenothing.com>
 * @description: Converts long hex to short hex
 * 
 * @before:
 *     .example {
 *         color: #000000;
 *     }
 * 
 * @after:
 *     .example {
 *         color: #000;
 *     }
 * 
 */

var CSSCompressor = global.CSSCompressor,
    rfullhex = /^#([0-9a-f]{6})$/i;

CSSCompressor.rule({

    name: 'Shrink Hex',
    type: CSSCompressor.RULE_TYPE_VALUE,
    group: 'Color',
    description: "Converts long hex to short hex",
    priority: CSSCompressor.PRIORITY_LOW,

    callback: function( value, position, compressor ) {
        var m = rfullhex.exec( value ),
            before = value,
            hex;

        if ( m ) {
            hex = m[ 1 ];

            // All alternating positions must match
            if ( hex[ 0 ] === hex[ 1 ] && hex[ 2 ] === hex[ 3 ] && hex[ 4 ] === hex[ 5 ] ) {
                value = '#' + hex[ 0 ] + hex[ 2 ] + hex[ 4 ];

                compressor.log(
                    "Converting long hex to short hex code '" + before + "' => '" + value + "'",
                    position
                );
                return value;
            }
        }
    }

});